Gabe Polsky’s documentary RED ARMY plays like a high-stakes sports match, with glory and heartbreak, and more than a few thrilling twists and reversals of fortune. It follows the Soviet Union’s premier hockey team, called the Red Army, through its peak years in the 1980s, when it boasted the formidable five-man lineup known as the Green Unit. Heading the Green Unit was defenseman Viacheslav “Slava” Fetisov, now a hard-nosed politician in Russia, with whom Polsky interviews extensively in the film. Through Fetisov’s story we come to understand the backbreaking and often soul-killing nature of the Red Army’s training, the team’s…